Invasion of Porphyromonas gingivalis strains into vascular cells and tissue

Abstract

Porphyromonas gingivalis is considered a major pathogen in adult periodontitis and is also associated with multiple systemic diseases, for example, cardiovascular diseases. One of its most important virulence factors is invasion of host cells. The invasion process includes attachment, entry/internalization, trafficking, persistence, and exit. The present review discusses these processes related to P. gingivalis in cardiovascular cells and tissue. Although most P. gingivalis strains invade, the invasion capacity of strains and the mechanisms of invasion including intracellular trafficking among them differ. This is consistent with the fact that there are significant differences in the pathogenicity of P. gingivalis strains. P. gingivalis invasion mechanisms are also dependent on types of host cells. Although much is known about the invasion process of P. gingivalis, we still have little knowledge of its exit mechanisms. Nevertheless, it is intriguing that P. gingivalis can remain viable in human cardiovascular cells and atherosclerotic plaque and later exit and re-enter previously uninfected host cells.

Keywords: P. gingivalis; invasion; vascular cells; vascular tissue.

Fig. 1

Scanning electron micrographs of bacteria in vascular biopsies from patients with periodontitis. (a) From aneurysmal wall with bacteria in a meshwork of fibers. (b) Aneurysmal wall with bacteria in fibers and remnants of intravascular plaque. (c) Rods with remnants of intravascular plaque on aneurysmal wall. (d) Aneurysmal wall with bacteria in fibers and remnants of intravascular plaque. (e, f) Aneurysmal wall with coccus-shaped bacteria in fibers and remnants of intravascular plaque. From Armingohar et al. (1).

Fig. 2

Transmission electron micrograph of P. gingivalis strain W83 entering and inside HCAEC after 2.5 h of coincubation. Arrows indicate P. gingivalis inside autophagic vesicles. Adherent and bacteria in the midst of entry are also visible.

Fig. 3

Diagram of proposed entry, trafficking, and persistence of strains of P. gingivalis that utilize the autophagic pathway in HCAEC.